Circumstellar structures in the eclipsing binary beta Lyr A - Gasdynamicalmodelling confronted with observations

A disentangling technique was applied to obtain an independent check on the amplitude of the radial-velocity curve of the more massive component of be ta Lyr derived earlier. This is crucial for the reliable determination of t he component masses and their separation. Currently the best available basi c physical properties of the binary were then defined. For them, 3-D gasdyn amical simulations of mass transfer between the binary components of beta L yr were calculated and confronted with the existing evidence of various cir cumstellar structures within the binary system. It turns out that the gasdy namical model is able to explain, in principle, the formation of the basic observed components of the circumstellar matter. This brings us one step fa rther to the understanding of this unusual object.